Heretofore, a band coupling has generally been used for coupling a container body and a container lid of a pressure container (see, for example, Japanese Laid-Open Patent Publication No. 11-255256). Also, band couplings, which are configured to enable a detachment operation to be performed easily and stably, have been proposed, for example, in Japanese Utility Model Publication No. 07-023415 and Japanese Laid-Open Patent Publication No. 2004-276979.
The band couplings proposed in Japanese Utility Model Publication No. 07-023415 and Japanese Laid-Open Patent Publication No. 2004-276979 are made up from a metallic annular retainer having a V-shaped groove, a metallic flexible band that is attached to an outer periphery of the retainer, and a tightening mechanism for tightening the flexible band. Therefore, the container body and the container lid are joined together using the retainer to clamp outer peripheries of respective flange sections of the container body and the container lid, which are placed in mutual abutment with each other, and then tightening the band by the tightening mechanism.